106 



ILLINOIS STATE DAIRYMEN'S ASSOCIATION. 



of experiments made with it indicate that it is unwise to use it. 

 In using a preservative for composite samples there is more or 

 less danger from accidental cases of poisoning, and in the selec- 

 tion of a preservative the less the danger from this cause the 

 better. The preservative powers of formaldehyde are equal to 

 those of corrosive sublimate and potassium dichromate. The 

 following taken from the results of an investigation in milk pre- 

 servatives and published in a bulletin (No. 32) of the Iowa 

 Experiment Station will give a comparison which will represent 

 the results of the investigation. The Mason fruit jars held one 

 pint of milk and the preservatives in the quantities as given 

 below were placed in each jar, then each day there was added 

 to each jar fifteen c. c. of milk to represent the composite 

 sample as taken in the creamery, the jars being shaken 

 each day to ensure the milk being mixed thoroughly. 



Quantity in each jar. Time preserved. 



Formaldehyde, 40 per cent. 



.ICC. 



13 



days 



40 " - 



.2 C. C. 



17 





40 - - 



.4 C. C. 



22 





40 - - 



.6 c. c. 



33 





40 " - 



.8 c. c. 



39 





40 " " 



I c. c. 



46 





Corrosive sublimate. 



k gram 



21 





( ( i i : 



1 4 i 

 2 



30 





n ( < 



I " 



48 





Potassium dichromate. 



•2 a 

 3 



24 





e. 



I *' 



33 





a a 



I* - 



47 





The above results show the preservative power of the sub^ 

 stances used compared one with the other. This experiment 

 was made during July, August, and September. The mean 

 temperature of the room was y6. 7 F. , with a minimum tem- 

 perature of 65 F., and a maximum temperature of Sy F., which 

 was as severe a test as could be made upon them. 



There has been recently published an investigation of a milk 

 preservative sold in England, called "Rhodin Purifier, " for which 



